JPH07134180A - Radiation measuring device - Google Patents

Abstract

PURPOSE:To automatically set an optimum smoothing period according to the fluctuation of dose rate by determining an integrating width from a distributed value arithmetically operated with a plurality of measured values including the present measured value at this point of time as elements, and integrating the measured values in the integrating width. CONSTITUTION:The detection signal of a radiation detector 10 is stored 12 in time series to regularly keep a counting rate (n0 shows the rate at present, n1, n2... show rates before this) within a fixed time from the present time, and it is outputted to an integrating part 14 and an adding part 16. The adding part 16 carries out addition in each period for distributed value operation, and the added value is stored 18 timewise. An integrating width judging part 20 sets thresholds N0+KN1<1/2>, N0-KN0<1/2> with an added value N0 as standard, judges the added value first exceeding either one of the thresholds back from this point of time, and outputs the period to the added value as an integrating width 100 to the integrating part 14. The integrating part 14 integrates all the counting rates in the width 100, and the result is averaged by a display arithmetic part 22. Further, the arithmetic part 22 multiplies the average value by a prescribed coefficient to calculate the dose ratio, and displays 23 it as measured value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation measuring apparatus, and more particularly to a radiation measuring apparatus capable of automatically optimizing an averaging period.

[0002]

2. Description of the Related Art For environmental radiation, etc., the dose rate thereof fluctuates drastically with time, and if the dose rate measured by a radiation measuring device is displayed as it is, its value cannot be read accurately. This tendency is particularly strong in digital displays.

Therefore, in the conventional radiation measuring apparatus, an averaging function is added and the display is made easy to see by smoothing. And, in a general device, the time constant can be switched,
The averaging period can be artificially switched according to the intensity of radiation dose rate fluctuations. Various methods are applied to the averaging (smoothing).

[0004]

In the conventional device,
If the averaging period is fixed, it is not possible to perform appropriate smoothing according to changes in the dose rate. Moreover, when the time constant is artificially switched, it is often not optimized and complicated. In particular, when operated by a person who is not familiar with the operation of the device, if the time constant is too large, the responsiveness deteriorates, and if the time constant is too small, the fluctuation is too rapid and it becomes difficult to read the value. .

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to provide a radiation measuring apparatus capable of automatically setting an optimum averaging period by following changes in dose rate. is there.

[0006]

In order to achieve the above object, the present invention provides a radiation detector, a storage means for storing measured values of detected radiation in time series, and a predetermined period of time returning from the present time. A variance value calculating means for obtaining a variance value for a plurality of measured values, an integration width determining unit for determining an integration width according to the variance value, and an integration unit for integrating the measurement values within the integration width to obtain an integration value. And a display for displaying a measurement result obtained from the integrated value.

[0007]

According to the above configuration, the variance value is calculated using a plurality of measurement values including the current measurement value as an element, and the period (integration width) relating to averaging is determined according to the variance value. Then, the measurement values within the integration width are integrated, the measurement result is calculated based on the integration value, and the measurement result is finally displayed.

In the present invention, the smoothing period can be set on the basis of the magnitude of the variation in the measured values. Therefore, when the variation is large, the integration width is increased to increase the degree of smoothing and the display can be easily seen. . On the other hand, if the variation is small, the integration width can be reduced to reduce the degree of smoothing and improve the responsiveness.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall construction of a radiation measuring apparatus according to the present invention. 2 shows the principle of the present invention. First, the principle of the present invention will be described with reference to FIG.

In FIG. 2, (A) shows the variation of the counting rate, which is a measured value of radiation, over time. That is, the horizontal axis is the time axis and the vertical axis is the count rate. Here, t indicates the sampling period of the A / D converter (not shown), and T indicates the period for calculating the variance value, as will be described later. In addition, T is set at each time,
The periods T overlap each other.

FIG. 3B shows a graph of the added value for each period T over time.

As shown in (A), the counting rate fluctuates with time, and if the measured value is displayed as it is,
The display is difficult to read.

Therefore, in the present invention, the magnitude (standard deviation) of the variation of the count rate is obtained, and the averaging period 100 is set based on the obtained magnitude. That is, if the T is assumed 3, the addition value N ₀ the current _{is, N 0 = n 0 + n} 1 + n 2 , and the its N ₀ as a reference, as the upper and lower threshold (upper) N ₀ + K Set √N ₀ (bottom) N ₀ −K√N ₀ . However, _ni is a count rate and K is a constant.

Then, as shown in (B), the cumulative width 100 is set from the current time point until the time when the upper threshold value or the lower threshold value is first exceeded. Next, the counting rates are integrated within the integration width, and the integrated value is finally divided by the number of counting rates to obtain the averaged counting rate.

That is, in the present invention, the optimum smoothing period is automatically set by linking the magnitude of the variation of the measured value with the magnitude of the integrated width.

Returning to FIG. 1, the detection signal from the radiation detector 10 is stored in the memory 12 after passing through an amplifier and a scaler. Here, the storage is performed in time series as shown in FIG. 2A, and the count rate within a fixed time from the current time is always held. That is, the memory 12
Is composed of, for example, a ring buffer. Note that FIG.
, The current measured count rate is indicated by n ₀ and the previous count rates are indicated by n ₁ , n ₂ ...

The output of the memory 12 is output to the addition unit 16 as well as to the integration unit 14.

The adder 16 performs conversion from FIG. 2A to FIG. 2B, that is, addition in each period T. In the figure, T = 3 is set for the sake of explanation, but T is preferably about 5 to 20, for example. The adder 16 can be basically configured by one adder by switching the input and the output.

The memory 18 stores the added values shown in FIG. 2B with time. Then, the integrated width determination unit 20
, Based on the addition value N _0, the threshold N ₀ + K√N ₀
And N ₀ −K√N ₀ are set, and after returning from the present time, the added value that exceeds one of the threshold values is first determined. Then, the period up to the added value is output as the integration width 100 to the integration unit 14.

On the other hand, the integrating unit 14 integrates all the counting rates within the integrating width 100 and outputs the integrated value to the display computing unit 22.

The display / calculation unit 22 performs averaging by dividing the integrated value by the integrated number. Then, the dose rate is calculated by multiplying the average value by a predetermined coefficient, and the calculated dose rate is displayed on the display 24 as a measured value.

Incidentally, the measurement value can be displayed by either digital display or analog display, but particularly in the case of digital display, automatic setting of smoothing is significant.
In the digital display, the significant significant digit portion and the other significant digit portion may be identified. Also, the size of the standard deviation may be displayed together. Various methods can be applied to the display form for that purpose.

[0024]

As described above, according to the present invention,
The optimum averaging period can be automatically set by following changes in the dose rate.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a radiation measuring apparatus according to the present invention.

FIG. 2 is a diagram showing the principle of the present invention.

[Explanation of symbols]

 12 memory 14 integrating unit 16 adding unit 18 memory 20 integrating width determining unit 100 integrating width

Claims (1)

[Claims] 1. A radiation detector, storage means for storing measured values of detected radiation in time series, and variance value calculation means for returning from the present time to obtain variance values for a plurality of measurement values within a predetermined period, An integration width determination unit that determines a temporal integration width according to the variance value, an integration unit that integrates measurement values within the integration width to obtain an integration value, and a display that displays a measurement result obtained from the integration value. And a radiation measuring apparatus comprising: